docs: def cmp_pkgrevno(package, revno, pkgcache=None):
      """Compare supplied revno with the revno of the installed package.
  
      *  1 => Installed revno is greater than supplied arg
      *  0 => Installed revno is the same as supplied arg
      * -1 => Installed revno is less than supplied arg
  
      This function imports YumBase function if the pkgcache argument
      is None.
      """
      if not pkgcache:
          y = yum.YumBase()
          packages = y.doPackageLists()
          pkgcache = {i.Name: i.version for i in packages['installed']}
      pkg = pkgcache[package]
      if pkg > revno:
          return 1
      if pkg < revno:
          return -1
      return 0